Prostaglandins play a major role in the inflammation process and the inhibition of prostaglandin production, especially production of PGG.sub.2, PGH.sub.2 and PGE.sub.2, has been a common target of antiinflammatory drug discovery. However, common non-steroidal antiinflammatory drugs (NSAIDs) that are active in reducing the prostaglandin-induced pain and swelling associated with the inflammation process are also active in affecting other prostaglandin-regulated processes not associated with the inflammation process. Thus, use of high doses of most common NSAIDs can produce severe side effects, including life threatening ulcers, that limit their therapeutic potential. An alternative to NSAIDs is the use of corticosteroids, which have even more drastic side effects, especially when long term therapy is involved.
Previous NSAIDs have been found to prevent the production of prostaglandins by inhibiting enzymes in the human arachidonic acid/prostaglandin pathway, including the enzyme cyclooxygenase (COX). Recently, the sequence of another heretofore unknown enzyme in the human arachidonic acid/prostaglandin pathway has been reported by T. Hla and K. Nielson, Proc. Natl. Acad. Sci, USA, 89, 7384 (1992) and named "cyclooxygenase II (COX II)" or "prostaglandin G/H synthase II". The discovery of an inducible enzyme associated with inflammation provides a viable target of inhibition which more effectively reduces inflammation and produces fewer and less drastic side effects. Cyclooxygenase II is inducible by cytokines or endotoxins and such induction is inhibited by glucocortoids (J. Masferrer, et al, Proc. Natl. Acad. Sci, USA, 89, 3917 (1992)). The 6-methoxy-2-napthylacetic acid metabolite of nabumetone has been found by E. Meade et al to selectively inhibit the COX II enzyme (J. Biol. Chem., 268, 6610 (1993)). In addition, Futaki et al (Prostaglandins, 47, 55 (1994)) have reported that N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide inhibits the COX II enzyme.
The cyclopentene compounds disclosed herein are such safe and also effective antiinflammatory agents furthering such efforts. The invention compounds are found to show usefulness in vivo as antiinflammatory agents with minimal side effects. The substituted cyclopentene compounds disclosed herein preferably selectively inhibit cyclooxygenase II over cyclooxygenase I.
1,2-Diarylcycloalkenes have been made and used for a variety of utilities. For example, U.S. Pat. No. 4,543,207 to Sato, et al., describes diphenyl cyclohexene as an electrical insulating oil additive.
U.S. Pat. No. 4,229,207, to Laanio, et al., describes 1,2-diphenyl-cyclohex-1-ene-4-carboxylic acid esters, specifically, 1,2-di(4-phenylsulfonic acid)cyclohex-1-ene-4-carboxylic acid ethyl ester. These ester compounds are reported to be effective as plant growth regulating agents and as post-emergent herbicides for controlling wild oats.
DE 4,212,628, published Oct. 21, 1993, describes 3,4-bis-alkylphenylcyclohex-3-enes as anti-tumor agents.
The synthesis of 3,4-diphenyl-.DELTA..sup.3 -cyclopentenone ethylene ketal is described as an intermediate for forming carbinols [E. J. Corey, et al., J. Amer. Chem. Soc., 85, 1788 (1963)]. 2,3-Bis-(4-hydroxyphenyl)-2-cyclopenten-1-one has been identified from the knot resin powder of Arqaucaria angustifolia [H. Ohash, et al., Phytochemistry, 31, 1371 (1992)].
Substituted 1,2-diphenylcyclopentenes have been synthesized for use in studies of their rotational behavior, includes specifically, 1-(2,4-Dimethylphenyl)-2-phenylcyclopentene [D. Y. Curtin, et al., J. Org. Chem., 36, 565 (1971)]. 1,2-Di-(2'-methoxyphenyl)-.DELTA..sup.1 -cyclopentene has been identified as an impurity in the synthesis of cannabinoids [O. P. Malik, et al., Ind. J. Chem., 14B, 975 (1976)].
1-(Substitutedphenyl)-2-phenylcyclopentenes have been synthesized to study their photochemical reactions into phenanthrene derivatives. Compounds with meta substituents, such as 1-(3-chlorophenyl)-2-phenylcyclopentene, are described in Somers, et al., J. Photochem. Photobiol., 48A, 353 (1989). Para substituents, including specifically 1-(4-fluorophenyl)-2-phenylcyclopentene, are described in Laarhoven, Pure & Appl. Chem., 56, 1225 (1984).